Display tunings of all rendered tracks

[Danielku15]

alphaTab currently only shows the tuning and chord diagrams of the first track. Would be nice if it shows the tunings of all displayed tracks side by side just like Guitar Pro.

[Danielku15]

Rendering of the tuning was "beautified" a bit and we render now tunings of all tracks displayed. The track name is shown above the tuning in case multiple tunings are displayed:

Chords of all tracks were already displayed, but there was an issue with the unique chord ids in alphaTex.